Synthetic tone musical instrument



March 12, 1929. 5, CABQT SYNTHETIC TONE MUSICAL INSTRUMENT Filed July 5,1918 5 Sheets-Sheet jut/Qtior SwasZZ @505 March 12, 1929. S..CABOTSYNTHETIC TONE MUSTCAL INSTRUMENT Filed July 5, 1918 v 3 Sheets-Sheetve7zz o7 e waZZ @505 KZI I v WOT'TC/Qy March 12, 1929.- s. CABOTSYNTHETIC TONE MUSICAL INSTRUMENT Filed July 5, 1918 3 Sheets-Sheet@OKZ/ I l l l J ZZZ/876567) Sea/Q55 6 Waltz/v W IPIRW U EFSZ PatentedMar. 12, 1929.

UNITED STATES SElVALL CABOT, OF BROOKLINE, MASSACHUSETTS.

SYNTHETIC TONE MUSICAL INSTRUMENT.

Application filed July 3,

This invention relates to musical instruments of the type in which aseparate sounder is provided for each tone or pitch of the scale, sothat the sounders may be brought into play separately or in any desiredcombination,

and sustained for any lengthof time, according to the score, the will ofthe performer in the case of manual playing, or according to therecorded interpretation in a perforated sheet or otherplaying agent ofan automatically operated mechanism.

Une object of my present invention is to provide an improved musicalinstrument of relatively small cost and small dimensions in comparisonto those of a pipe-organ, but capable of attaining all the musicallyuseful results of which a pipe-organ is capable. Another object is toprovide an instrument that will produce desirable tonal effects notheretofore obtainable from a pipe-organ.

The pipe organ, which is the best known example of an instrument forproducing music of various qualities, is complex, expensive, andoccupies great space, for the reason that it requires a distinct set ofsounders for each quality of tone provided.

The extreme multiplicity of sounders'has been reduced in some degree bythe electromagnetic instrument known as the Choralcelo, and disclosed insome degree of perfection by U. S. Letters Patent 1,098,983.

It has been proposed (see U. S. Letters Patent 1,110,012 and 1,181,486)to utilize the natural harmonics in strings vibrated with frequenciesthat are multiples of the frequency of the fundamental pitch to whichthe strings were tuned, to obtain a change in tone quality, but the netresult did not produce sufiicient volume or contrast to competefavorably with those of a pipe organ.

More specifically, an object of the invention is to provide a musicalinstrument with which synthetic tones are produced by compounding thewaves generated by harmonically related sounders each vibrated at itsnormal or fundamentalfrequency.

A feature of the invention consists in means for bringing into play,each at its normal frequency of vibration, two or more sounderssimultaneously by the action of aprimary controller. which, in the caseof a manually played instrument, would be a key or pedal. I prefersounders that execute simple harmonic motion in the pitches of theequally tempered scale. The sounders so brought into play are related toeach other 1918.- Serial No. 243,239.

in pitch just like so many partials of a compound tone appertaining tothe primary controller. Thus, with .one possible combination, a primarycontroller may bring into play, not only the sounder having the pitchappertaining thereto, but those correspond ing in pitch to the secondand third partials of a compound tone of that pitch. Each sounder,therefore, would contribute its simple harmonic motion of predeterminedregulatable amplitude to the production of a synthetic tone.

Another feature consists in controlling and varying the relativeintensities of the sounders played conjointly as aforesaid, to the endthat each fundamental and each harmonic will have the requisite force,but no more, to produce the tonal eifect desired.

.Thus, by varying the number and the harmonic relation of the combinedsounders, and by varying the relative forces with which they are played,a great variety of tone qualities may be produced. The invention is notlimited to any number or to'any one harmonic relation of sounders playedconjointly, nor to any relative force with which they are played, but Ihave found that when provision is made for combining five or any lessnumber of sounders, each with four different relative forces, it ispossible to approximate very closely the tone qualities of all the wellknown musical instruments, and to produce many new tone qualities thatare musically useful.

Preferably, and as shown. the sounders are controlled and operated bythe agency of electric wiring, and. accordingly another feature of theinvention consists in an arrangement of electrical circuits includingprimary controllers with which to execute the playing, and secondarycontrollers or selectors, such as draw-stops. each of which, when inoperative position. determines which and how many harmonically relatedsounders will operate conjointly and also the relative forces with whichthey will operate when brought into play by the primary controllers. I

The intensity and the combinations of the component sounds arepreferably predetermined by the wiring of the several draw stops, thusrelieving the performer from all mental and physical effort other thansetting the draw stop that bears the name of the tone quality desired.

The illustrated apparatus includes a set of sounders'representing,collectively, all the notes of an equally tempered chromatic scale whichmay have any desired range. lissuxn ing that the instrument is intendedto be played manually there will be a separate sounder for each ltcy ofthe manual.

lly suitable electrical connections a single movement ot a draw stopwill combine the sounders that correspond in frequency of vibration tothe several partials of a compound tone, and will also determine theintensities with which the combined Sounders will operate.

1 have found that more satisfactory nulsical results are obtained bycompounding simple harmonic motions simultaneously, and with differentdegrees of amplitude, than by translating complex wave motions intocorrespondingly complex air motions. So far as I am aware no apparatushas been produced heretofore to accomplish this result in a musicalinstrun'icnt, and I desire the broadest possible interpretation of theclaims hereinafter set forth.

Referring to the accompanying drawings, which are diagramumtic, l havedivided the complete showing for two notes and two different tonequalitics into three figures, to

avoid complexity.

On the drawings.

Figure 1 represents a wiring diagram that is complete as to one pitchand two tone qualities thereof- Although rovision is made herein foronly two combinations of Sounders and only two different intensities ofeach sounder, this showing is sufficient to indicate how provision maybe made for additional combinations and additional intensitics.

Figure 2 represents a wiring diagram that is complete as to twocontiguous pitches and two different intensities for each sounder, thedraw stop connections being omitted for the sake of simplicity. The drawstops and their five contacts corresponding to the first five partialsof each itch are intended to have the same tonal e sets as the drawstops included in Figure. 1. I

Figure 3 represents a wiring diagram illustrating the relation in whichthe sounding circuits are cross-connected to provide for operating thesounders to furnish harmonics in addition to fundamentals;

For convenience of expression the word partial is herein used to meanthe component sound furnished by each of the SOlll'KlClS contributingits motion to the production of a compound tone, with no distinctionbetween the fundamentals and the harmonics.

In the use of reference characters, numbers and letters are combinedaccording to the Following scheme: a letter preceding a numeralsignifies that the element indicated is duplicated for each note of thechromatic scale, while a numeral followed by a letter mousse indicatesan clcmcntfor coupling hormone cally related soundcrs.

A source of direct current, such as a hattery, is indicated at l).-Battcry leads and ii are the principalconductors of the soundingcircuit, which is represented by relatively heavy lines. 'lfh rmsounding circuit is used to identity t cuit that operates the sounder-s,The con oiling circuits by which the partials arc cor lined and theirdililcrent intensities selected, ind those by which they are broughtinto play, are represented by relatively light lines.

v in Figure 1 l have shown a primary controller or switch 70, such asthe key of a manual. lit will be understood that in the case of anautomatic player some other form of primary switch could be providedinstead of a manual key. The sounder for the fundamental pitch, or firstpartial, appertaining to the key is indicated at G. In the presentinstance the sounder is represented as comprising a nodally mountedsteel bar g havin a resonator r'. The soundcrs indicated at (3 G G, andG are harmonically related to the fundamental sounder, the superiors 13,and 29, representing the numerical order of the semi-tones in thechromatic scale, assuming that the fundamental tone is regarded as thefirst. In like manner these superiors have the same significancewherever they occur. All the Sounders included in a set or scale arepreferably alike in kind, but differ in size and pitch, but for the sakeof simplicity, I have omitted reference characters appertaining to thesteel bars and resonators excepting those of sounder w. The steel bar ofeach sound generator is tuned to execute simple harmonic motion of anormal l re ucncy corresponding to its position in the c romatic scale.Each sounder is caused to vibrate, in every instance, with its normalt'rc uency, and never with a multiple thereof, an for this purpose Iprefer electromagnetic exci'ters such as those indicated by the letter awith appropriate numerical superiors corresponding to their ositions inthe scale. Direct current from attery b is utilized to energize theexciters, the current being interrupted as to each exciter with afrequency corresponding to that of the sounder excited thereby.Continuously driven rotary interruptcrs c (with appropriate nu mcricalsuperiors) are arranged in series with the excitcrs respectively. Theinterrupted current passes through adjustable rhcostats R et cct'cra,which are intended to be adjusted collectively by the performer at theinstrument to regula e the volume of sound.

.The manual key k is'not included in the sounding circuit, but is in acontrolling circuit 12, one side of which is connected to battery lead10, and the other side to battery lead 11. Each key circuit includes arelay magnet, that for the circuit of key 70 being indicated at m. Thismagnet, when energized, connects battery lead 10 to a plurality ofbranches 1, 2, 3, t and that couple sounders G G G G and G therebycausing said sounders to operate simultaneously, and since they are allharmonically related to each other and give simple tones respectively,they produce a synthetic tone having no undesirable partials.lnthepresentinstance,havingshown branches for producing the first formharmonies in addition to the branch for producing the fundamental tone,I have provided with each primary controller a sounding switch havinglive movable contacts all of which are responsive to the magneticinfluence of the magnet m. These five contacts, indicated respectivelyat 1 2 8 al and 5 close the connections between battery lead andbranchcircuits l, 2, 3, l and 5.

in the present instance I have shown provisions for giving two dilierentrelative intensities from each sounder, although it will be understoodthat there maybe provisions for a greater number of intensities. Ashereinbefore stated I have found that tour different intensitiesfor'each sounder afford substantially all the different tone qualitiesthat will be useful, and while it have shown provisions tor twodifierent intensities, it will be understood that additional intensitiesmay be provided by duplicating the branches now to be described.

Each of the branches 1, 2, 3, d and 5 is divided into two branches, thelatter being indicated (reading from left to right) i, l, l, 2', 1 2' 15 l, and lilaving shown means for regulating the intensities of eachsounder with two difi'erent degrees, it have used capital letters wherethe greater'intensity occurs, and small letters where the lesserintensity occurs, thus indicating by the rank of letter thecorresponding rank of intensity.

Referring to the branches or branch 1 it will be observed that I? doesnot contain any resistance, this branch being intended to make theconnection of the sounding circuit to the exciter or the fundamentaltone with relatively great intensity, whereas the branch 2" includesresistance intended to decrease'the intensity of the fundamental tone,subject to the control aft'orded by the draw stops; All the branches areinitially disconnected from the 'exciters but are connected with saidexciters in any desired combination by pulling the draw stops.Connection is made between the subordinate branches and the exciters bymultiple switches, ten of which are represented in cachet the figures bythe reference characters 1, 1 2 2 3 3 l l 5 5 The fact that it haveshown'ten of these multiple switches is due to the fact that the showingprovides for five partials and two intensities of each partial, but inpractice, assuming that theinstrument is equipped for four intensitiesfor each of five partials there would be twenty multiple switches. Inother words there will be a separate multiple switch for each intensityof each sounder. Each multiple switch is provided with anelectro-magnet, which, when energized, completes the connection betweenthe exciter and the branch with which the multiple switch is associated.Each multiple switch has a num ber of movable contacts equal to thenumber of primary controllers c et cctra. Figure 2 shows the multipleswitches as having only two movable contacts because only two primarycontrollers are represented. 'llwo draw stops are indicated at and @neside of each draw stop is connected to battery lead 10, and each stop,when moved to a circuit-closing position, engages five stationarycontacts, the latter'being the terminals of regulating circuits 1 2 3 land 5 respectively, These regulating circuits correspond respectively tothe first five partials of a compound tone and there may be as few or asmany controlling circuits as desired, within the total number providedfor, according to the combination desired. In the pres ent instance drawstop D makes connections through the maximum number of regulatingcircuits, whereas draw stop l)" makes connections through but threecircuits, the latter beingindicated at l 3 and 5*. Referring to thecircuits controlled by draw stop .u, circuit P is connected to magnet l,the lower grade or rank of the letter m incl-- eating a relatively lowdegree of intensity of the sounder brought into play therethrough.Circuit 2 is connected to the magnet 2 grade or rank of the letter Mindicating a relatively high degree of intensity afforded thereby. in asimilar manner the circuits 3*, 4 and 5 are, connected to magnets 3 iand 5", respectively. According to this combination draw stop D willselect a low degree of intensity for the fundamental tone, a high degreeof intensity for the first har-- monic, a high degree of intensity forthe sec- 0nd harmonic, a low degree of intensity for the third harmonic,and-a low degree'ot' inten sity for the fourth harmonic, the net resultas to tone quality when the degree of res1st- .ance in the branchesailected thereby is correctly predetermined, being equivalent to that ofthe oboe. When the draw stop D is in circuit-closing position, multipleswitches 1 2 3 4: and 5 are moved to circuit-closing position by theirrespective magnets thus completing the electrical connections betweenall the exeiters a a etc, and the desired rcsistance coils ofthe'sounding circuits. The synthetic tone produced by this combinationcomprises a weak first partial (resistance 5 a strong second partial(resistance l), a strong third partial fourth partial (resistance 2')and a wear: fifth partial (resistance 6 (resistance 1 a weak:

lit)

Ill

' though, for the sake All the magnets that are associated with themultiple switches are connected to a com mon return wire, which, inturn, is connected to battery lead 11. The complete circuit ofregulating circuit 1 without regard to direction, or polarity, is asfollows: from battery I) to battery lead 10, draw stop D, regulatingcircuit 1 magnetl common return to battery lead 11, back to the oppositeside of battery Z).

Each multiple switch distinguished by S or c, with an appropriatenumeral prefix, includes one pair of contacts for each key of the manualor other principal controller, al-

oi': simplicity, l-have shown only one pair or contacts for eachmultiple switch in Figure 1 because this figure includes only one manualkey. in Figure 2, however, I have shown two manual keys, l, 71: togetherwith con'iplete wiring connections for both of them. In this tigure'llhave therefore shown each multiple switch as having two pairs ofcontacts, and further explanation concerning them will occur in duecourse. g

Referring to Figure 1, when the desired draw stop is moved tocircuit-closing position it selects not only the desired combination ofpartials, but also the desired intensity for each sounder, the selectionof intensity being direct because each sounding circuit has a multipleswitch and companion magnet for each resistance branch. All the soundingcircuits are thus com leted excepting at the points controlled b t 1econtacts 1 2, 3 4, and 5 of the scan ing switch, and the instrument isthus prepared for operation. 'W hen the primary switch it is closed,thus energizing magnet m, 25, l, and 5 are closed, and current will thenflow from battery 5) through battery lead 1G, sounding circuits 1, 2, 3,d and 5, the branches previously selected by the draw step, through allthe connected exciters of the sounders, through all the interruptersthen in circuit, and through battery lead ll returning to battery. 3yreason of th fact the described apparatusproducessyntheti ctones andaffords individual'control off each constituent tone, it great varietyof com ound tones is made possible and no undesirable partials need everbe produced. As soon as the key 70' is released its magnet m is(lo-energized, and the sounding switch controlled thereby opens thecircuits 1, 2, 3, t, and 5. Draw step ii) calls for only three simpletones "for each note (see Figure 1), viz, a strong fundamental tone, aweak octave quint, and a weak tierce, the synthetic effect producedthereby being similar to that of the clarinet. I

The showing of Figure 2 diiiters from that of Figure l in that it isincomplete as to the regulating circuits controlled by the drawstops,and includes an additional key 70 and all the additional elementsle The fundamental tone 0 the note corthe sounding circuits 1i, 2, f

a pertaining to c resses responding to 70 is produced by the sounder Giwhile the harmonics are produced by the sounders G, G, G andrespectively. The exciters of these five sounders are-indicated at a, a,a, a and a, while the interruptors that belong thereto are indicated at0?, 0 ,0 amend 0 The numerical superiors, it is to be remembered,indicate the relative order of the elements according to the positionsof the sounders in the chromatic scale.

Referring to the multiple switches as shown by Figure 2, each switch isshown as having one movable contact for each of the two manual keysshown. Had it been attempted to show the full number of keys for acomplete manual there would have been one movable contact for each keyonthe manual, with corresponding duplication of the sounding switchesand the branches and subbranches running therefrom to the stationarycontacts of the multiple switches. In this respect to complete theequipment would require merely adding a sounding circuit for eachadditional sounder and primary switch, and adding: to the contacts ofthe multiple switches accordingly, so that each key would cause currentto energize the whole number of exciters potentially coupled to it bythe draw stop in circuit-closing position. Figure 2 shows how thecurrent from battery 6 is caused to energize one or both relay magnetsm, m and how the current is consequently caused to energize the exeitersthat are brought into play by the manual keys and controlled in thefirst instance, as to combination and intensity, by the draw stop.

llnTaccor-dance with common practice with pipe organs, an instrumentembodying the present invention may have two or more mannals, and whenmore than one manual is provided the elements and wiringshown by thedrawings will be du 'ilicatcd, with the exception of the battery b, foreabh manual.

Figure 3 shows how the sounding circuits are interconnected so that eachsounder may furnish a tone equivalent to a third partial as when G isbrought into play by (see the same showing in Figure 1) and equivalentto a first artial, second partial, fourth partial, and ifth partial aswhen G is brought into play by 10 70, 70 and 7cre speclively. Here, theminus sign indicates that the controller is below 70' in the scale, andthe numeral indicates its order or position reckoned trom Zc.,Therefore, sounder G furnishes the fundamental for 70 the first harmonicfor 70 the second harmonic "for in, third harmonic for Zrand fourthharmonic for 76 The showing of sounding circuit 1 (broken lines) ascontrolled by is is the same as in Figure 1 excepting that to it areadded the sounding circuits 2, 3, 4 and 5 controlled by 76 70, 70 andkrespectively.

till

sounders respectively.

By reason of these interconnections any sounder may be played by two ormore primary controllers simultaneously, and when so played its playingforce or intensity is equal to the sum of all the forces combined by theplaying connections. Hence, for example, G may furnish the fundamentalfor 70 while furnishing the third partial for is, and its playing forcein such case will be that ail'orded by circuit 1 of 70 plus thatafforded by circuit 3 of is. As a general rule this interconnectedrelation obtains throughout the scale of sounders and relay switches,although, obviously, their number would be less in the two or more loweroctaves of the scale.

I claim:

1. A musical instrument comprising sounders adapted to furnish a musicalscale, electro-magnetic means for exciting the sounders individually,said means including playing switches to which the sounders are relatedas fundamentals respectively, relay switches responsive to the controlof the playing switches respectively to connect for conjoint operationwith each fundamenetal sounder one or more other sounders harmonicallyrelated thereto, resistance elements,-

means for putting said resistance elements into circuit selectively toproduce. a predetermined tone quality from each group of sounders putinto play conjointly as afore said, and one or more controllers eacharranged to determine which harmonic sounder or sounderswill be put intoplay conjointly with each fundamental sounder and simultaneously todetermine which resistance elements will be put into the circuits ofsaid 2. A musical instrument comprising sounders adapted to furnish amusical scale, playing switches to which said sounders are relatedrespectively as fundamentals, means controlled by said playing switchesfor coupling automatically with each fundamental sounder forco-operation therewith a plurality of other sounders harmonicallyrelated thereto and related as fundamentals to other said playingswitches, playing controllers for selecting simultaneously apredetermined combination of sounders, harmonieallyrelated to eachother, andmeans cont-rolled by said playing controllers to give saidsounders so selected relatively"difierent intensities.

3. A musical instrument comprising sounders adapted to furnish a musicalscale and the harmonics thereoi each of said sounders being soconstructed as to produce only one simple ,harmonic motion or sine wavein the air, and means for exciting the sounders individually, said meansincluding playing switches to which the sounders are related asfundamentals, respectively, a plurality of tone-qualitycontroller-switches, one for each separate prcdetern'iined tone qualityin which the instrument may be played, multiple contacts co-operatingwith said controller switches equal in number to the largest number ofharmonically related sounders it is desired tosimultaneously soundtogether, electrical wiring to said multiple contacts and apparatusincluded therein for selecting for each said tone-qualitycontroller-switch which harmonically related sounders shall be groupedtogether and for simultaneously determining the relative intensities ofsaid sounders so grouped.

4. In a musical instrument having sounders adapted to produce simpleharmonic motion in the air and to furnish a musical scale, playingswitches to which said sounders are related, respectively, asfundamentals, means controlled by said playing switches for operatingthe sounders, and unitary means to connect for conjoint combinations ofsounders harmonically related to each other and simultaneously toregulate the intensities relatively to one anothgr of the tones producedby the sounders.

In testimony whereof I have afi'ixed my signature.

SEWALL OABOT.

operation predetermined

